Fixing parser issues related to import

This fixes both #122 and #123.
#122 was linked to the fact that '...' is seen by the lexer as an Ellipsis token. To keep changes to a minimum two new import_from_dots rules have been added to deal with the fact that we can have DOT or ELLIPSIS (tested up to seven '.')
#123 was related to a 'double' typo error import_as_name was used in place of import_as_names but the ast.Module was built with [names] so that for a single name it worked.

NB : You may have to delete the parsetab.py because it is not always correctly updated when the parser in imported if the rules gave changed.